Method of forming frozen spheres in a force-free drop tower

Abstract

A method of forming hollow glass spheres S shaped by the effects of surface tension acting on bubbles of glass in its molten state; the method is characterized by the steps of establishing a downwardly flowing stream of air accelerated at a one-G rate of acceleration through a drop tower 10, introducing into the stream of air free-falling bubbles B of molten glass, and freezing the bubbles in the stream as they are accelerated at a one-G rate of acceleration.

What is claimed is: 
     
       1. A method of forming solid spheres from a hardenable liquid material, the steps comprising: A. establishing a flowing stream of gaseous fluid with said stream flowing in a substantially vertical downward direction;   B. introducing droplets of hardenable liquid material into said stream with the droplets accelerating in the direction of said stream and at a common rate of acceleration with said stream, which rate is substantially one-G; and   C. cooling said droplets a sufficient amount within said stream to harden said droplets.   
     
     
       2. A method as defined in claim 1 in which said droplets comprise bubbles. 
     
     
       3. A method as defined in claims 1 or 2 wherein said fluid comprises ambient air and said material comprises molten glass. 
     
     
       4. A method as defined in claims 1 or 2 wherein said stream of fluid comprises a stream of ambient air drawn at a one-G rate of acceleration vertically downwardly through a cooled drop tower, and said droplets of material comprises free-falling bubbles of molten glass. 
     
     
       5. A method as defined in claims 1 or 2 wherein said stream of fluid comprises a stream of gas downwardly accelerated through a drop tower, and said droplets of material comprise hollow, free-falling droplets of glass characterized by a capability of being frozen in said stream. 
     
     
       6. A method for forming hollow glass spheres shaped by the effects of surface tension acting on bubbles of glass in its molten state comprising the steps of: A. establishing a downwardly flowing stream of air accelerated at a one-G rate of acceleration;   B. introducing into said stream of air free-falling bubbles of molten glass; and   C. freezing the bubbles in the stream as they are accelerated at a one-G rate of acceleration.